Grassland desertification is an important environmental issue that has detrimental impacts on the sustainable development of grasslands and human residential environments. Soil microbial community structure might dramatically change during desertification processes because microorganisms are one of the major drivers of ecological processes through their interactions with plants and soil. However, knowledge on the driving factors of microbial diversity changes during the desertification process in alpine grasslands is still lacking. Using a spatial sequence instead of a time successional sequence method, five desertification gradients in alpine steppe were chosen to investigate the changes in soil properties, plants and microbial communities during grassland desertification and to determine the factors that drive microbial community changes. Community coverage, species diversity indices and aboveground biomass gradually decreased from potential to severely heavy desertification gradients (HDs), while species richness and belowground biomass showed unimodal patterns (p < .05). Soil water content and total nitrogen showed gradual decreasing trends, while soil bulk density and gravel content showed opposite trends (p < .05). In addition, both the Shannon diversity index and the Chao1 richness index of soil bacteria increased gradually. The structural equation model showed that of the factors, soil total nitrogen (82.3% of total effect) and soil bulk density (41.4% of total effect) were the most important soil factors affecting soil bacterial diversity. However, community aboveground (43.4% of total effect) and belowground production (13.9% of total effect) were not the primary factors affecting soil microbial diversity. This result suggests that soil microbial diversity during grassland desertification is primarily driven by changes in soil properties, and the effects of vegetation composition and production are relatively small. These findings contribute to the mechanistic understanding of soil microbial diversity by linking changes in soil properties and plant production during desertification processes in alpine ecosystems.

中文翻译：

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土壤特性而非植物产量严重影响了青藏高原沿荒漠化梯度的土壤细菌群落多样性

草原荒漠化是重要的环境问题，对草原和人类居住环境的可持续发展具有不利影响。在沙漠化过程中，土壤微生物群落结构可能会发生巨大变化，因为微生物通过与植物和土壤的相互作用而成为生态过程的主要驱动力之一。然而，仍然缺乏关于高寒草原荒漠化过程中微生物多样性变化驱动因素的知识。使用空间序列而非时间序列序列方法，选择了五个高寒草原荒漠化梯度，以调查草地荒漠化过程中土壤特性，植物和微生物群落的变化，并确定驱动微生物群落变化的因素。p  <.05）。土壤含水量和总氮呈逐渐下降趋势，而土壤容重和砾石含量呈相反趋势（p <.05）。此外，土壤细菌的香农多样性指数和Chao1丰富度指数均逐渐增加。结构方程模型表明，在影响因子中，土壤总氮（占总效应的82.3％）和土壤容重（占总效应的41.4％）是影响土壤细菌多样性的最重要土壤因子。然而，地上社区（占总效应的43.4％）和地下生产（占总效应的13.9％）不是影响土壤微生物多样性的主要因素。这一结果表明，草地荒漠化过程中土壤微生物的多样性主要是由土壤性质的变化驱动的，植被组成和生产的影响相对较小。